Which of the following is an example of an Ohmic conductor?

• A. Wires
• B. Diodes
• C. Light bulbs
• D. Thermistors

Answer: (A)

Ohm's law describes a constant resistance where current is directly proportional to voltage. A metal wire behaves this way when its temperature stays essentially the same: the resistance stays roughly constant, so doubling the voltage doubles the current. That steady, linear V–I behavior is what makes a wire an Ohmic conductor.

Diodes don’t follow this simple linear relationship—their current stays very small until a forward voltage is reached, then rises rapidly in a nonlinear way, and in reverse they block current. Light bulbs don't stay linear either because the filament heats up as current increases, changing its resistance and bending the V–I line away from a straight, proportional shape. Thermistors are designed to change resistance with temperature, so their V–I relationship is highly non-linear.

So a wire is the example that best fits Ohm's law: its resistance is effectively constant over the typical operating range, giving a straight, proportional V–I relationship.